We compare the proposed FL scheme with the FL FDMA scheme with equal bandwidth \(b_1=\cdots =b_K\)  (labelled as `EB-FDMA'),
the FL FDMA scheme with fixed local accuracy \(\eta =1/2\)  (labelled as `FE-FDMA'), and the FL time division multiple access (TDMA) scheme in [1]} (labelled as `TDMA').
Fig. REF  shows how the delay changes as the maximum average transmit power of each user varies.
We can see that the delay of all schemes decreases with the maximum average transmit power of each user.
This is because a large maximum average transmit power can decrease the transmission time between users and the BS.
We can clearly see that the proposed FL scheme achieves the best performance among all schemes.
This is because the proposed approach jointly optimizes bandwidth and local accuracy \(\eta \) , while the bandwidth is fixed in EB-FDMA and \(\eta \)  is not optimized in FE-FDMA.
Compared to TDMA, the proposed approach can reduce the delay by up to 27.3%.
